Krishna
Covers some ground covered by books like The Particle Garden, Quantum and Uncertainty. Also it is a book that retains your interest and is much more famous than the two quoted above.
Starts right away with the dichotomy and incompatibility between quantum physics and that of the Theory of Relativity and how the string theory reconciles both. This book, unlike the Particle Garden is an unapologetic supporter of the string theory.
Wonderful illustrations of Theory of Relativity bring it to life. For instance how Grace and Tom(?) are floating in pure space and how you cannot tell who is moving and who is stationary. In fact, even if both are moving, each will think that the other is moving. Even more astounding fact about how time slows for both people (one thinks that the other has a slow watch and the other thinks the same), astounding illustrations of how the space (length) of the vehicle is also changed by motion. Amazing. The description of why the speed of light is the limit is unbelievably amazing. It is simple to understand but so unconventional that the mind refuses to accept it. If anyone other than Einstein or people like Brian Green had told me this, I would have laughed that person out of the room!
He also brings us up to date on why Newton’s theories were revolutionary in their own time until Einstein gave us the bigger picture and how, in that picture, some of the former’s theory proved to be wrong.
An excellent description of the space time continuum and the time warp and space warp ensues. We have heard these terms in many scientific books or journals but this seems to be one of those rare books that explains it in a very plain and accessible language. It is great to read and finally understand the finer points of Einstein’s breakthroughs.
The dichotomy of how gravity does not mesh with Einstein’s theory of relativity and how he next came up with the general theory of relativity to fold it in is also brilliantly told. What does it mean to say that any mass curves the space and time? Where does gravity come into all this? This book probably has one of the best explanations.
He then turns his powers to explaining black holes and event horizon. When you are very close to the event horizon of black hole, due to the immense gravity, the clock will run significantly slower and this is what is known as ‘time being warped’. Brilliant.
If you crush sun to the size of Manhattan, you get a black hole. But a teaspoon of that substance will weigh the same as Mount Everest. (Can you be simpler in an explanation than this? It is hard to do. )
Brian then turns to quantum theory, to work his magic of making it plain through a clear and simple explanation. But quantum theory itself is messy with it’s discussion of probabilistic positioning and ‘sum of all outcomes’ reasoning that make no sense in a macro level.
He then outlines the conflict between quantum and relativity theories. Then the start of the string theory is surprising. Scientists suddenly found that all the observed properties either obey the theory of relativity (large scale) or quantum theory (small scale) but not both. The attempts to bring the two together always resulted in the answer of ‘infinity’.
However, initially, the weak particle behaviour was also found to follow Euler’s formula of the patterns for the oscillation of strings (or matter). This surprising fact led to investigations which resulted in a much more astounding result – by varying the frequency of oscillations, the properties of other forces (including gravity) can be simulated. So started the thought. Can all the particles be composed of tiny (Plank length which is smaller than observable by today’s technologies) ‘strings’ that oscillate at different frequencies to create different particles? This theory has not been fully completed (only approximations exists and therefore sceptics abound) but is fascinating as far as it has gone.
He explains why string theory makes sense – it explains most known phenomena. It resolves the conflict between quantum theory (one of ever changing quantum changes in a microscopic scale) and special theory of relativity (smooth space time continuum) by showing that the strings have to have a minimal length (Plank length, too tiny to see with our present capabilities) where the quantum fluctuations are smoothed out. It also predicts incredible tensions for both graviton (a so-far-theoretical equivalent of photon for gravity) and elementary string, and how they cancel out when they form quarks, neutrons etc which are far lighter than the tension would suggest.
Just when you were thrilled about understanding the string theory well for the first time ever, Brian goes on to talk about Supersymmetry and how Supersymmetry, married to String Theory, produces Superstring Theory. It is also supremely fascinating. The super partners (eg Selectron for electron, Sphoton for photon etc) have not been found experimentally yet. Given that they should be, according to calculation, heavier than the normal particles, it is surprising that the current particle accelerators have not found them, which makes some scientists doubt the Supersymmetry theory. In addition, there are five explanations of how superparticles are integrated into String theory, all of which agree with current experimental results! The latest advances (at least they were latest when the book was written!) in this new field indicate that all the five explanations may point to the same underlying phenomena – a fact that is not unknown to science.
OK, now you are feeling really good about your capability to understand this thing and Brian launches into multiple dimensions and hidden dimensions without a pause. And wonder of wonders, he is able to make it as explicit to a lay person as it would ever get! He talks about how three dimensions would be really puzzling in a two dimensional world by giving an analogy of a garden hose and an ant.
Once you ‘understand’ the extra dimensions and why we do not see them, Brian turns his prodigious explanatory powers towards how it melds with string theory. Even though coming out in favour of string theory as the possible theory that will, in future, explain it all, he also gives us the scepticism from the likes of Richard Feynman and others, and explains why brilliant minds are unable to accept this theory – he concedes that they have a point.
He also talks about how the quantum mechanics evolved its own mathematics to account for string theory and talks about two different vibrations – one akin to strings like closed rubber bands vibrating on a surface and the other like bands wound up over the circular dimension (like a hose) and vibrating along the circumference. A bit confusing, but clear explanations are provided. In a way, he speculates that even the known dimensions (three axes) extend all over the universe but ‘may curve and come back to meet in a circle beyond our capacity to measure these!
The book gets difficult when he talks about how the five string theories are different manifestations of the same underlying principle. You realize that we (our scientists) do not know much about the ‘real’ character of the universe as they are only able to do the approximate calculations.
He describes how supersymmetry solved some problems in string theory that were previously unsolvable by today’s mathematics and how it showed that out of the five different string theory solutions, three were shown to be symmetric with each other or self. It also showed that though string theory predicts 10 dimensions, in certain cases of the constant, an eleventh dimension shows up. All these are of course esoteric math issues, as no one can really measure them. It is still interesting, which is a tribute to the power of explanation of the author, which is without parallel in the complex world of string theory.
Even so, some portions go over a layman’s head. The one dimensional space collapsing to a zero dimensional space and transforming back to another one dimensional space (a doughnut to two points to a sphere) is enough to make anyone get completely befuddled.
Even in the depth of this advanced jungle, Brian Green manages to amaze us with the talk about the possibility of entropy in a Black Hole and it emitting elementary particles like photon, thereby becoming a ‘melting black hole’
He then turns his attention to the origin of the universe and the Big Bang theory. Talks about the Cosmic Background Radiation and how it was formed and why it is useful now.
And goes into amazing discussions of multiverse and the various theories up to now (Well, at least up to about 15 years ago when the book was written).
All in all a great book and one of the best in terms of explaining the recent advances in the world of particle physics.
9/10
‘- – Krishna